by Clare Baldwin
December 16, 2008
SAN FRANCISCO (Reuters) - The Earth's
protective magnetosphere has two large holes that are letting in
disruptive solar winds, scientists said on Tuesday.
Understanding how these holes form will help them better predict the
electrical storms that cause power grid blackouts and the aurora,
activity that will peak in 2012 as sunspots hit their maximum level.
Scientists at the American Geophysical Union meeting in San
Francisco said they had been entirely wrong about how solar
particles that cause the storms were entering the Earth's
The magnetosphere is a bubble of magnetism that surrounds Earth and
protects us from solar wind.
Scientists once believed that the particles entered when the sun's
magnetic field was aligned opposite to that of the Earth's. But
findings presented at the meeting show that 20 times more solar
particles enter the Earth's magnetic field when it is aligned in the
same direction as the sun's magnetic field.
The alignment causes the two magnetic fields to connect and tears
holes in the Earth's magnetic field over the poles.
"What we observed was the breach in
the levee," said Jimmy Raeder, a physicist at the
University of New Hampshire. "This has taken us completely by
In June 2007, NASA's five
THEMIS spacecraft probes flew
through one of the tears just as it was opening. Sensors recorded a
torrent of solar wind particles streaming into the magnetosphere,
"The opening was huge - four times
wider than Earth itself," said Raeder. "This kind of influx is
an order of magnitude greater than what we thought was
Most of the particles are deflected back
into space, but some circulate in the magnetosphere, get energized,
and cause electrical storms that trigger power grid outages, cause
problems for aircraft flying over the poles, and can damage
satellites in geosynchronous orbit.
"There's a bigger risk because we
have more stuff in space now," said Raeder.
Scientists said that the majority of
solar storms take place midway through and on the tail end of the
This 11-year cycle of activity
is at its minimum now and electrical storms will be at their
peak in 2012.